Abstract

Understanding the drifting motion of a small semi-submersible drifter is of vital importance regarding monitoring surface currents and the floating pollutants in coastal regions. This work addresses this issue by establishing a mechanistic drifting forecast model based on kinetic analysis. Taking tide–wind–wave into consideration, the forecast model is validated against in situ drifting experiment in the Radial Sand Ridges. Model results show good performance with respect to the measured drifting features, characterized by migrating back and forth twice a day with daily downwind displacements. Trajectory models are used to evaluate the influence of the individual hydrodynamic forcing. The tidal current is the fundamental dynamic condition in the Radial Sand Ridges and has the greatest impact on the drifting distance. However, it loses its leading position in the field of the daily displacement of the used drifter. The simulations reveal that different hydrodynamic forces dominate the daily displacement of the used drifter at different wind scales. The wave-induced mass transport has the greatest influence on the daily displacement at Beaufort wind scale 5–6; while wind drag contributes mostly at wind scale 2–4.

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Foundation item: This work was supported by the National Key Research and Development Program of China (Grant No. 2017YFC0405401), the National Science & Technology Pillar Program (Grant No. 2012BAB03B01), the Fundamental Research Funds for the Central Universities, Hohai University (Grant No. 2014B30914), and the Natural Science Foundation of Jiangsu Province (Grant No. BK2012411).

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Acknowledgements

The authors would like to thank Prof. DING Xian-rong for his contribution to the field experiment. Wind data used in this study were provided by the experiment center of the College of Harbor, Coastal and Offshore Engineering, Hohai University.

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